3. Are the transmissions in these things pretty reliable? (My truck has had a 5th wheel mount in the bed so i assume it has towed one around.) How much does this effect my transmission?

4. Are there any things that i should be closely aware of with this new truck? (My last vehicle was a 2001 civic dx. so i know nothing about my truck except that it will should help me out with hauling of my commercial fishing nets and totes and other duties associated)

Sounds like you got yourself a pretty sweet ride. For a service manual, I would look on ebay first. You could probably get one there a lot cheaper than from a dealership. Since you have an automatic transmission, I would keep an eye on it, especially since it has a 5th wheel and has been pulling heavy sometime in its life. With most diesel engines backed by an auto, the transmission is the weak link. If you feel anything weird coming from the trans, get it looked at before it turns into something really serious. As for air cleaners, I am a firm believer in the K&N, or similar cold air intake set-ups. I have 2 gas engines with cold air set-ups, and the performance and fuel milage improvemens are noticable. When going for engine oil filters, personally I like Fleetguard and Wix filters the best. For oil, I would go with the Shell Rotella T or Valvoline Premium Blue oils at 15W40 weight. As for a fuel filter, I would use the same. Your truck probably has a "water in fuel" or WIF sensor. Make sure it is at least hooked up. Getting a batch of bad fuel can cause all sorts of problems in your fuel system. It also isn't a bad practice to occasionally cracking open the drain on the bottom of the filter to check for water. I would occasionally use a fuel conditioner to keep the tank clean. Normal maintence times is something you would have to consult a manual about. Again, go to ebay first. If you want to do anything else to improve power and performance, give me a shout. I have plenty of resources and tips.

i purchased my 96 powerstroke new. 211,000 miles leater it runs better than new, i have the owner's manual and the shop manual. any thing i can help you with let me know. by the way , my truck is all original except for the water pump and alternator. i tow a 16,000 lb 5th wheel. service and driving skill will make it last